Compliant constrained headband spring

ABSTRACT

A compliant constrained headband spring for audio headphones includes a headband spring element and a stiffness enhancing element coupled to the headband spring element. The compliant constrained headband spring exhibits a first stiffness in an open position and a second stiffness greater than the first stiffness when closed beyond a predetermined point.

TECHNICAL FIELD

Aspects and implementations of the present disclosure are directedgenerally to audio headphones and specifically to headbands for same.

BACKGROUND

Over-the-ear audio headphones (e.g., around-ear and on-ear headphones)typically include a pair of earcups including speaker elements and aheadband coupling the earcups to one another. The headband is worn overthe head of a user and positions the earcups on or about the ears of theuser. The headband may include a compliant mechanism, for example, aleaf spring, that applies force through the earcups to the head and/orears of the user to maintain the earcups in place on or about the earsof the user and acoustically couple the earcup acoustics to the ears ofthe user.

SUMMARY

In accordance with an aspect of the present disclosure, there isprovided a compliant constrained headband spring of a headband for audioheadphones. The compliant constrained headband spring comprises aheadband spring element and a stiffness enhancing element coupled to theheadband spring element. The compliant constrained headband springexhibits a first stiffness in an open position and a second stiffnessgreater than the first stiffness when closed beyond a predefined pointat which terminal ends of the headband spring element are at apredefined distance from one another.

In some examples, in the absence of external force and in the absence ofthe stiffness enhancing element, the headband spring element closes to apoint at which earcups mounted on the terminal ends of the headbandspring element contact one another. The stiffness enhancing element hassufficient stiffness to prevent the compliant constrained headbandspring from closing to a point at which earcups mounted on the terminalends of the headband spring element contact one another.

In some examples, the predefined distance is within a range of betweenabout 50 mm and about 121 mm.

In some examples, the stiffness enhancing element is disposed on anouter surface of the headband spring element over at least a centralregion of the headband spring element. The stiffness enhancing elementmay comprise a strap coupled to the headband spring element atconnection points on opposing sides of the headband spring element. Thestiffness enhancing element may be coupled to a retainer block coupledto the headband spring element.

In some examples, a terminal end of the stiffness enhancing elementcomprises a portion with a cross-sectional area greater than across-sectional area of a central portion of the stiffness enhancingelement. The terminal end of the stiffness enhancing element may bedisposed within a groove in the retainer block. The terminal end of thestiffness enhancing element may be configured to travel through thegroove as the compliant constrained headband spring is opened and/orclosed. The terminal end of the stiffness enhancing element may beretained in the retainer block by a shoulder defined in the retainerblock.

In some examples, the compliant constrained headband spring furthercomprises a feature to adjust an effective length of the stiffnessenhancing element. The feature may comprise a threaded screw disposed inthe retainer block that engages threads on the terminal end of thestiffness enhancing element. The feature may comprise a plurality ofapertures defined in the headband spring element at different distancesfrom a center portion of the headband spring element, and configured toreleasably retain a base of the retainer block.

In some examples, the stiffness enhancing element is coupled to theheadband spring element at connection points on opposing sides of theheadband spring element. The stiffness enhancing element may beconfigured to displace from the central region of the headband springelement upon opening of the headphones, forming a gap between a surfaceof the headband spring element and the stiffness enhancing element.

In some examples, the stiffness enhancing element comprises at least oneof a fiber reinforced polymer, a metal, a wire, an elastomeric materialor a braided cable.

In some examples, the stiffness enhancing element is disposed on aninner surface of the headband spring element over a central region ofthe headband spring element. Terminal ends of the stiffness enhancingelement may be disposed on tabs extending from the inner surface of theheadband spring element. The terminal ends of the stiffness enhancingelement may displace from inner surfaces of the headband spring elementupon opening of the headband, forming gaps between the terminal ends ofthe stiffness enhancing element and the inner surfaces of the headbandspring element.

In some examples, the stiffness enhancing element comprises a firstportion and a second portion. An arc length adjustment device may bedisposed between the first portion and the second portion.

In some examples, the compliant constrained headband spring is includedin a pair of audio headphones.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 is a schematic illustration of audio headphones on the head of auser;

FIG. 2 is a schematic illustration of an example of a pair of audioheadphones;

FIG. 3 is a schematic illustration of another example of a pair of audioheadphones;

FIG. 4A is a schematic illustration of an example of a compliantconstrained headband spring for a pair of audio headphones in an openstate;

FIG. 4B is a schematic illustration of the compliant constrainedheadband spring of FIG. 4A in a closed state;

FIG. 4C is a schematic illustration of a comparative example of aheadband spring for a pair of audio headphones in a closed state;

FIG. 4D is an isometric view of another example of a compliantconstrained headband spring for a pair of audio headphones;

FIG. 4E is a partial cross-sectional view of a retainer block element ofthe headband spring of FIG. 4D;

FIG. 4F is an isometric view of another example of a compliantconstrained headband spring for a pair of audio headphones;

FIG. 4G is a partial cross-sectional view of a retainer block element ofthe headband spring of FIG. 4F;

FIG. 4H is an isometric view of a portion of another example of acompliant constrained headband spring for a pair of audio headphones;

FIG. 5A is an elevational view of another example of a compliantconstrained headband spring for a pair of audio headphones;

FIG. 5B is a isometric view of the compliant constrained headband springof FIG. 5A;

FIG. 5C is a plan view from beneath the compliant constrained headbandspring of FIG. 5A;

FIG. 5D is an isometric view of the headband spring element of theheadband spring of FIG. 5A;

FIG. 5E is an elevational view of the headband spring of FIG. 5A in anopened state;

FIG. 5F is an elevational view of another example of a compliantconstrained headband spring for a pair of audio headphones;

FIG. 5G is a plan view from beneath the spreader knob of the headbandspring of FIG. 5F; and

FIG. 5H is a cross-sectional view through the headband spring of FIG. 5Falong line H-H.

DETAILED DESCRIPTION

Aspects and implementations disclosed herein are not limited to thedetails of construction and the arrangement of components set forth inthe following description or illustrated in the drawings. Aspects andimplementations disclosed herein are capable of being practiced or ofbeing carried out in various ways.

Aspects and implementations disclosed herein are generally directed toaudio headphones (referred to hereinafter as simply “headphones”) and toheadbands for same. The headphones may be over-the-ear headphones suchas on-ear or around-ear headphones or banded in-ear headphones.Alternatively, the headphones may have ear pieces with acoustic driversthat are that are located off a user's ears but with a headband toconnect and retain the ear pieces in a desired position. Aspects andexamples of the audio headphone headbands disclosed herein may providefor increased comfort and aesthetics as compared to presently knownaudio headphone headbands.

For the sake of clarity the following terminology to be used throughoutthis disclosure is defined. FIG. 1 depicts a schematic of a pair ofheadphones 100 disposed on the head 200 of a user. Headphones 100include a pair of earcups 105 and a headband 110. The portion of theheadband 110 of the headphones 100 disposed above the head 200 of theuser is referred to herein as the central portion 115 of the headband110. The portions of the headband 110 proximate to or coupled to theearcups 105 are referred to herein as end or terminal portions 120 ofthe headband 110. The headband 110 exerts forces F on the earcups 105 ina direction toward the head 200 of the user. The direction of forces Fis referred to herein as an inward direction. A direction opposite tothat of forces F is referred to herein as an outward direction. When theterminal portions 120 of the headband 110 and/or the earcups 105 and aheadband 110 move in the inward direction, this is referred to herein asthe terminal portions 120 of the headband 110 and/or the earcups 105closing or moving toward a closed position. When the earcups 105 are ina position such that the earcups 105 are close to one another, typicallywhen the headphones are removed from the head 200 of the user and noexternal force is applied to the headband 110, the headphones 100 areconsidered to be in a closed position. The headphones 100 may also beconsidered to be in a closed position when the headband 110 exerts noforce biasing the earcups 105 toward or away from one another. When theterminal portions 120 of the headband 110 and/or the earcups 105 of theheadband 110 move in the outward direction, this is referred to hereinas the terminal portions 120 of the headband 110 and/or the earcups 105opening or moving toward an open position. Linguistic variations of thisterminology, for example, changes in tense, utilization as nouns, verbs,or adjective, etc., or application of these terms to other elements orfeatures disclosed herein should not be considered to change the meaningof these terms.

The forces F that hold the earcups 105 of headphones 100 against theears and/or head 200 of a user are typically generated by forming atleast a portion of the headband 110 with or as a spring. The headbandspring often includes an arcuate length of spring material, for example,spring steel or another compliant material. The strength of the forces Fgenerated by a headband spring may be dependent on factors such as thedimensions, for example, thickness, width, degree of curvature, etc. ofthe headband spring and/or the material of construction of the headbandspring.

In some examples, the he earcups 105 may be secured directly to oppositeterminal ends 120 of the headband spring. In other examples, the earcups105 may be indirectly coupled to the headband spring by one or moreintervening elements. The headband spring may be housed within a shell,lining, cover or housing of the headband 110. Some examples ofheadphones 100 include headbands 110 having cushioning to increase thecomfort of the headphones when worn by a user. For the sake of clarity,headband shells, linings, covers, housings, and cushioning are notillustrated in the figures accompanying this disclosure.

Some headbands 110 are compliant and offer fairly consistent clampingforce, comfort, and stability across a full range of user head 200sizes, for example, with earcup separations of between 121 mm to 155 mmwhen the headphones are on a user, which spans the 5th to 95thpercentile for adult human head (ear-to-ear) widths. To achieve thisresult, a high compliance headband spring is used. Such a highcompliance headband spring may exert a clamping force of between about200 grams and about 400 grams when worn on a user's ears (for users inthe 5th to 95th percentile for adult human head (ear-to-ear) widths),and in some examples, about 275 grams for a median-sized human head. Inother examples a high compliance headband spring may exert a clampingforce of between about 3.5 Newtons (N) and about 4.5 N when worn on auser's ears (for users in the 5th to 95th percentile for adult humanhead (ear-to-ear) widths). With such a high compliance spring, it takessignificantly more deflection to achieve a desired preload and stabilityfor small heads. The result from this high compliance spring is aheadband 110 that, in the absence of an external force, compresses theearcups 105 together in a closed state when the headband is in a freestate off of the head 200 of a user. The closed state of headphones 100including such a high compliance headband spring 125 is illustratedschematically in FIG. 2.

The look of the closed state of the headphones 100 illustrated in FIG. 2is considered less aesthetically pleasing than desired to some users.For example, some users of headphones 100 prefer to wear theirheadphones 100 about the neck when not in use and consider it to beaesthetically pleasing that there be a gap between the earcups 105 whenthe headphones 100 are worn about the neck. Such a look is illustratedschematically in FIG. 3. In some existing headphones 100 including highcompliance headband springs 125, for example, as illustrated in FIG. 2,when worn about the neck, the headphones 100 may close so much that theysqueeze the neck and cause discomfort. Further, in some instances, it isundesirable that the earcups 105 of headphones 100 contact one anotherwhen in a closed state because friction between the earcups 105 maycause wear and/or damage to the earcups 105.

Other examples of headphones 100 include headbands 110 that maintain theearcups 105 spaced from one another when off head and in a free state,for example, as illustrated schematically in FIG. 3. Examples ofheadband springs 125 utilized to achieve this look are much stiffer thanthe high compliance headband spring 125 utilized in the example ofheadphones 100 illustrated in FIG. 2. Such stiffer headband springs 125often yield inconsistent levels of comfort and stability across a rangeof user head 200 sizes. Such stiffer headband springs 125 also oftendeliver higher clamping force when worn, for example, between about 400grams and about 700 grams (for 5th to 95th percentile human head(ear-to-ear) sizes), or in other examples, between about 5 N and about 8N (for 5th to 95th percentile human head (ear-to-ear) sizes), which maybe less comfortable for a user than the high compliance headband spring125 utilized in the example of headphones 100 illustrated in FIG. 2,especially for users with larger heads.

In accordance with some aspects and examples disclosed herein, it ispossible to maintain consistent spring force across multiple head sizes(i.e. maintain the level of comfort and stability offered by existingheadbands including high compliance headband springs, for example, asillustrated in FIG. 2) with a headband that maintains earcups 105 spacedfrom one another when the headphones are off head. Some aspects andexamples disclosed herein provide for the consistent spring force acrossmultiple head sizes exhibited by high compliance headband springs whilealso providing improved parking comfort around the neck. In accordancewith some aspects and examples disclosed herein, when worn about theneck of a user, the headband 110 will maintain the earcups 105 spacedfrom one another and not squeeze the neck of the user.

In accordance with some aspects and examples disclosed herein, aheadband spring 125 for a headphone 100 may be modified to include astiffness enhancing member that effectively increases the stiffness ofthe headband spring 125 as the headband spring 125 closes, transitionsfrom an open to a closed state, or closes beyond a state of opennessexhibited when worn on the head 200 of a typical user (a user having anear-to-ear spacing within the 5th percentile to the 95th percentile ofear-to-ear spacing of adult human users). In some examples, thestiffness enhancing member effectively increases the stiffness of theheadband spring 125 as the headband spring 125 closes to a point atwhich terminal ends 120 of the headband spring 125 are less than about155 mm from one another, less than about 121 mm from one another, orbetween about 50 mm and about 100 mm from one another. In some examples,the degree of openness at which the stiffness enhancing membereffectively increases the stiffness of the headband spring 125 may beadjustable, for example, to be at a point at which terminal ends 120 ofthe headband spring 125 are anywhere between about 0 mm and about 155 mmor more from one another. In some examples, the modified headband spring125 may exhibit substantially similar or the same stiffness as anon-modified headband spring 125 of comparable material(s) anddimensions when worn on the head 200 of a user, but exhibit increasedstiffness as compared to the non-modified headband spring 125 whenclosed to a state where terminal ends 120 of the headband spring 125 arecloser together than when worn on the head 200 of the user.

In some examples, a conventional high compliance headband spring 125(hereinafter, a headband spring element 125) may be modified to includea stiffness enhancing member on an upper and/or lower surface of acentral portion 115 of the headband spring element 125. In someexamples, the stiffness enhancing member is a high tensilestiffness/modulus and flexible strap that keeps the headband springelement 125 of a pair of headphones 100 from closing when in a freestate off of the head 200 of a user while allowing the earcups 105 tocompress onto the head and/or ears of a user when the headphones 100 areworn by the user. In other examples, the stiffness enhancing member is aflexible member that is under a state of tension and elongation when theheadband spring 125 is closed in a state where terminal ends 120 of theheadband spring 125 are closer together than when worn on the head 200of the user and/or at distance from one another that would be exhibitedwhen worn on the head 200 of a typical user. The modification to theconventional headband spring 125 may have very little to no impact onthe spring force when pulling the earcups 105 apart or wearing theheadphones 100. In some examples, the stiffness enhancing memberexhibits very little or no creep to maintain the degree of openness ofthe headband spring element 125 in a free state off head over time.

FIG. 4A illustrates a modified headband spring 130 in an open state, forexample, as worn on the head 200 of a user, including a stiffnessenhancing member comprising a high stiffness/modulus, low creep strap135 coupled to an upper or outer surface 145 of an otherwise unmodifiedheadband spring element 125 at coupling points 150 on either side of acentral portion 115 of the headband spring 130. While the strap 135 isillustrated as being coupled to an upper or outer surface 145 of theheadband spring element 125, it could also be coupled to a lower orinner surface of the headband spring element 125. The coupling points150 may be provided at an intermediate point between the central portion115 of the headband spring 130 and the outer ends of the headband spring130 as illustrated in FIGS. 4A and 4B, or the coupling points 150 may beprovided closer to the outer ends of the headband spring 130, so thatthe strap 135 spans most or all of the headband spring 130. In the openconfiguration, the strap 135 is pushed upward and forms a space or gap140 between the upper surface 145 of the headband spring element 125 andthe strap 135. When headphones 100 including the modified headbandspring 130 are removed from the ears and head 200 of a user, theheadband spring 130 closes into a configuration illustrated in FIG. 4B,such that there is a gap between the ends of the headband spring 130,where earcups may be mounted. The headband spring 130 is prevented fromclosing to a greater degree than what is illustrated in FIG. 4B by thestrap 135. The closed state of the headband spring 130 is more open thanthe closed state that the headband spring element 125 would exhibit inthe absence of the strap 135, illustrated in FIG. 4C. The earcups 105are not illustrated in FIGS. 4A-4C for clarity.

In some examples, the strap 135 may be formed from a high tensilestiffness, flexible, and low creep polymer or composite, for example,fiberglass or a carbon fiber reinforced epoxy. In some examples thestrap 135 may be formed from a metal or alloy, for example, spring steelof a same or different grade than that of headband spring element 125.In some examples, the strap 135 comprises a wire or a cable, forexample, a braided metal cable, in some instances, a braided steelcable. In some examples, the strap 135 comprises a fiber or group offibers, for example, a glass fiber or braided glass fibers, a carbonfiber or braided carbon fibers, or fibers or braided groups of fibers ofother materials. In other examples, the strap 135 comprises a compliantmaterial, for example a strip or body of rubber, an elastomericmaterial, or other material that may exhibit an increase in a forceresisting further elongation and/or an increase in elastic modulus asthe strip or body is elongated.

The strap 135 may be secured to the headband spring element 125 at theconnection points 150 by welding, rivets, screws, nuts and bolts, clips,hinges, or other mechanical fasteners known in the art. In otherexamples, one of the strap 135 and the headband spring element 125 mayinclude a slot, groove, or grooves and the other of the strap 135 andthe headband spring element 125 may include a protrusion or protrusionsthat slide through the groove(s) upon opening and closing of theheadband spring 130, for example, as illustrated in FIG. 4E or FIG. 5H.The protrusion or protrusions may freely slide through the groove(s),thus not impacting the stiffness of the headband spring 130 until theheadband spring 130 is closed to a degree at which the protrusion orprotrusions reach an end of the groove or grooves and cannot travelfurther and thus increase the stiffness of the headband spring 130. Theprotrusion or protrusions may be retained in the groove or grooves by anexpanded width head or terminal portion that cannot fit through thewidth of the groove. For example, as illustrated in FIG. 4D and FIG. 4E(showing a partial cross section of the retainer block of FIG. 4D), aheadband spring element 125 may include one or more retainer blockelements 155 coupled to the headband spring element 125. An end portionof the stiffness enhancing element 135 having a greater cross-sectionalarea than a central portion of the stiffness enhancing element 135, forexample, a widened and/or thickened end portion 160 of the strap 135,may freely pass through an aperture 165 in one of the retainer blockelements 155, for example, in the direction of arrow 170 in FIG. 4E,when the headband spring 130 is opened. The widened and/or thickened endportion 160 of the strap 135 may be constrained from moving apredetermined distance opposite to the direction of arrow 170 when theheadband spring 130 is closed beyond a predefined point by a shoulder175 internal to the retainer block element 155.

The headband spring 130 may include an arc length adjustment device tofine tune the openness and/or effective stiffness of the headband spring130. As illustrated in FIGS. 4F and 4G, an adjustment mechanism 180, forexample, a thumb nut or other wheel-like actuator or adjustment screwmay be mounted in one or more of the retainer block elements 155.Internal threads 185 on the thumb nut 180 may engage threads 190 on theoutside of the expanded end portion 160 of the strap 135 to move theexpanded end portion 160 of the strap 135 into different positionswithin the aperture 165 in the retainer block element 155. In someexamples, the thumb nut 180 may be sized and/or the aperture 165 may bepositioned such that the thumb nut 180 does not protrude into the user'shead side (the inside) of the headband spring element 125. In otherexamples, the thumb nut 180 may include a portion that protrudes intothe user's head side (the inside) of the headband spring element 125 asillustrated in FIG. 4G, but is located in a position where there isnormally a spacing between the headband spring element 125 and theuser's head so the thumb nut 180 would not contact the user's head.

In a further example, fine tuning the openness and/or effectivestiffness of the headband spring 130 may be accomplished by adjustingthe position of one or more of the retainer block elements 155 on theheadband spring element 125. For example, as shown in FIG. 4H, theheadband spring element 125 may be provided with multiple apertures 195into which a retainer block element 155 may be fitted, for example, witha reversible snap fitting or forming the base of the retainer blockelement 155 to adjust the tension applied by the strap 135 to theheadband spring element 125 or a degree of closure of the headbandspring element 125 at which the strap 135 would engage the headbandspring element 125 and increase the stiffness of the headband spring130. Other stiffness adjustment mechanisms are also contemplated, forexample, a lever actuated buckle or a ratcheting device that provide fora position of a retainer block element 155 to be adjusted.

In another example, for example, as illustrated in FIGS. 5A, 5B, and 5Ca modified headband spring 230 may be formed with a stiffness enhancingelement disposed on an inner surface 225 i of a headband spring element225. While the stiffness enhancing element is illustrated as beingdisposed on an inner surface 225 i of headband spring element 225, thestiffness enhancing element could also be disposed on an outer surfaceof headband spring element 225. The headband spring element 225 may besubstantially similar to and formed from substantially the samematerial(s) as headband spring element 125. The stiffness enhancingelement includes a body or material strip 235 that is stiff incompression and/or in tension. The material strip 235 may be formedfrom, for example, a low creep polymer or composite, for example,fiberglass or a fiber (for example, carbon fiber) reinforced epoxy. Inother examples, the material strip 235 may be a compliant material, forexample, rubber, an elastomeric material, or another material thatexhibits an increase in a force resisting further compression and/orelongation and/or an increase in elastic modulus as the strip or body iscompressed and/or elongated.

The material strip 235 is connected to the headband spring element 225by a protrusion 240 on the material strip 235 that passes through and/oris secured in an aperture 245 in the central portion 115 of the headbandspring element 225. In other examples, the material strip 235 isconnected to the headband spring element 225 by one or more protrusions240 disposed in additional or alternate positions than that illustrated.In some examples, the protrusion 240 is mushroom shaped or otherwiseshaped such that it snaps in place in the aperture 245. End portions 250of the material strip 235 may rest on or be secured to tabs 255extending inward from the inner surface 225 i of the headband springelement 225 between the central portion 115 of the headband springelement 225 and terminal portions 250 of the headband spring element225. The headband spring element 225 is illustrated without the materialstrip 235 in FIG. 5D to better illustrate the tabs 255 and associatedtab apertures 260 and aperture 245. The material strip 235 increases thestiffness of the modified headband spring 230 as compared to thestiffness of the headband spring element 225 in the absence of thematerial strip 235 when the headband spring 230 is closed beyond apredefined point.

In other examples, the end portions 250 of the material strip 235 may besecured to the headband spring element 225 by protrusions passingthrough slots in the headband spring element 225 (or by protrusions fromthe headband spring element 225 that pass through slots in the materialstrip 235). In such examples, portions of the material strip 235 mayslide relative to portions of the headband spring element 225 as themodified headband spring 230 is opened or closed. In some examples, theprotrusions may engage ends of the slots upon closing the headbandspring 230 past a predetermined closing point. The modified headbandspring 230 may thus exhibit increased stiffness due to interaction withthe material strip 235 as a user attempts to close the modified headbandspring 230 beyond the predetermined closing point. For example, themodified headband spring 230 may include retainer block elements 155such as those illustrated in FIGS. 4D-4H disposed on internal sides ofthe headband spring element 225 and engaging the end portions 250 of thematerial strip 235, which, in some examples, includes enlargedcross-sectional area terminal portions, similar to expanded thicknessend portion 160 of the strap 135 illustrated in FIGS. 4E and 4G.

In other examples, the end or terminal portions 250 of the materialstrip 235 are not fixedly secured to the inner surface 225 i of theheadband spring element 225 or the tabs 255. As the modified headbandspring 230 is opened beyond a predetermined point the end portions 250of the material strip 235 may disengage from the inner surface 225 i ofthe headband spring element 225 or the tabs 255 and a gap or gaps mayform between the end portions 250 of the material strip 235 and theinner surface 225 i of the headband spring element 225 and/or the tabs255. This is illustrated in FIG. 5E. The end portions 250 of thematerial strip 235 may thus only engage the inner surface 225 i of theheadband spring element 225 or the tabs 255 and increase the stiffnessof the modified headband spring 230 when the modified headband spring230 is closed beyond the predetermined point.

The end or terminal portions 250 of the material strip 235 may beprovided at an intermediate point between the central portion 115 of theheadband spring 230 and the outer ends 120 of the headband spring 130 asillustrated in FIGS. 5A-5C, or the end or terminal portions 250 may beprovided closer to the outer ends 120 of the headband spring 230, sothat the material strip 235 spans most or all of the headband spring230.

The headband spring 230 may include an arc length adjustment device tofine tune the openness and/or effective stiffness of the headband spring230. For example, as described above, the end portions 250 of thematerial strip 235 may include enlarged cross-sectional area terminalportions, similar to expanded thickness end portion 160 of the strap 135illustrated in FIGS. 4E and 4G above that are retained in retainer blockelements 155 such as those illustrated in FIGS. 4D-4H above. The endportions 250 of the material strip 235 may include threaded portionsthat engage threads of an adjustment mechanism 180, for example, a thumbnut or other wheel-like actuator or adjustment screw that may be mountedin one or more of the retainer block elements 155 as illustrated in FIG.4G above.

In another example, as illustrated in FIG. 5F and FIG. 5G, the materialstrip 235 may be split into two portions and an adjustable spreadermechanism, for example, spreader knob 265 may be mounted in a gap formedbetween the two portions of the material strip 235. A base portion 270of the spreader knob 265 may be thinner in a first direction X₁ than ina second direction X₂. Turning of the spreader knob 265 to disposeeither the thinner or the thicker portion of the base portion 270between the two portions of the material strip 235 would bias the twoportions of the material strip apart to different extents, thusproviding for changing an effective length and/or state of compressionof the two portions of the material strip 235 and thus adjusting thestate of openness of the headband spring 230 when not worn on a user'shead and/or adjusting the tension applied to the user's head when theheadband spring 230 is worn. In some examples, the portions of the strip235 may slide along the headband spring element 225 and maintain contactwith the headband spring element 225 by being pressed against theheadband spring element 225 by a housing (not shown) of the headband. Inother examples, the portions of the strip 235 may slide along theheadband spring element 225 while being retained in notches or recesses275 formed in the portions of the strip 235 as illustrated in FIG. 5H.Other examples of mechanisms for adjusting a distance between the twoportions of the material strip 235 are also contemplated, for example, ascrew passing through the ends of the two portions of the material strip235 that may be turned to adjust the spacing between the two portions ofthe material strip 235.

Having thus described several aspects of at least one implementation, itis to be appreciated various alterations, modifications, andimprovements will readily occur to those skilled in the art. Suchalterations, modifications, and improvements are intended to be part ofthis disclosure, and are intended to be within the spirit and scope ofthe disclosure. One or more features of any one example disclosed hereinmay be combined with or substituted for one or more features of anyother example disclosed. Accordingly, the foregoing description anddrawings are by way of example only.

The phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. As used herein, theterm “plurality” refers to two or more items or components. As usedherein, dimensions which are described as being “substantially similar”should be considered to be within about 25% of one another. The terms“comprising,” “including,” “carrying,” “having,” “containing,” and“involving,” whether in the written description or the claims and thelike, are open-ended terms, i.e., to mean “including but not limitedto.” Thus, the use of such terms is meant to encompass the items listedthereafter, and equivalents thereof, as well as additional items. Onlythe transitional phrases “consisting of” and “consisting essentiallyof,” are closed or semi-closed transitional phrases, respectively, withrespect to the claims. Use of ordinal terms such as “first,” “second,”“third,” and the like in the claims to modify a claim element does notby itself connote any priority, precedence, or order of one claimelement over another or the temporal order in which acts of a method areperformed, but are used merely as labels to distinguish one claimelement having a certain name from another element having a same name(but for use of the ordinal term) to distinguish the claim elements.

What is claimed is:
 1. A compliant constrained headband spring of aheadband for audio headphones, the compliant constrained headband springcomprising: a headband spring element; and a stiffness enhancing elementcoupled to a retainer block coupled to the headband spring element anddisposed on the headband spring element in at least a central region ofthe headband spring element, a terminal end of the stiffness enhancingelement disposed within a groove in the retainer block and comprising aportion with a cross-sectional area greater than a cross-sectional areaof a central portion of the stiffness enhancing element, the terminalend of the stiffness enhancing element configured to travel through thegroove as the compliant constrained headband spring is opened and/orclosed, the compliant constrained headband spring exhibiting a firststiffness in an open position and a second stiffness greater than thefirst stiffness when closed beyond a predefined point at which terminalends of the headband spring element are at a predefined distance fromone another.
 2. The compliant constrained headband spring of claim 1,wherein, in the absence of external force and in the absence of thestiffness enhancing element, the headband spring element closes to apoint at which earcups mounted on the terminal ends of the headbandspring element contact one another, and wherein the stiffness enhancingelement has sufficient stiffness to prevent the compliant constrainedheadband spring from closing to a point at which earcups mounted on theterminal ends of the headband spring element contact one another.
 3. Thecompliant constrained headband spring of claim 1, wherein the predefineddistance is within a range of between about 50 mm and about 121 mm. 4.The compliant constrained headband spring of claim 1, wherein thestiffness enhancing element comprises a strap coupled to the headbandspring element at connection points on opposing sides of the headbandspring element.
 5. The compliant constrained headband spring of claim 1,further comprising a feature to adjust an effective length of thestiffness enhancing element.
 6. The compliant constrained headbandspring of claim 5, wherein the feature comprises a threaded screwdisposed in the retainer block that engages threads on the terminal endof the stiffness enhancing element.
 7. The compliant constrainedheadband spring of claim 5, wherein the feature comprises a plurality ofapertures defined in the headband spring element at different distancesfrom a center portion of the headband spring element, the plurality ofapertures configured to releasably retain a base of the retainer block.8. The compliant constrained headband spring of claim 1, wherein thestiffness enhancing element is coupled to the headband spring element atconnection points on opposing sides of the headband spring element. 9.The compliant constrained headband spring of claim 8, wherein thestiffness enhancing element is configured to displace from the centralregion of the headband spring element upon opening of the headphones,forming a gap between a surface of the headband spring element and thestiffness enhancing element.
 10. The compliant constrained headbandspring of claim 1, wherein the stiffness enhancing element comprises atleast one of a fiber reinforced polymer, a metal, a wire, an elastomericmaterial or a braided cable.
 11. The compliant constrained headbandspring of claim 1, included in a pair of audio headphones.
 12. Acompliant constrained headband spring of a headband for audioheadphones, the compliant constrained headband spring comprising: aheadband spring element; a stiffness enhancing element coupled to aretainer block coupled to the headband spring element and disposed onthe headband spring element in at least a central region of the headbandspring element, the compliant constrained headband spring exhibiting afirst stiffness in an open position and a second stiffness greater thanthe first stiffness when closed beyond a predefined point at whichterminal ends of the headband spring element are at a predefineddistance from one another; and a feature to adjust an effective lengthof the stiffness enhancing element, the feature comprising a threadedscrew disposed in the retainer block that engages threads on a terminalend of the stiffness enhancing element.
 13. The compliant constrainedheadband spring of claim 12, wherein the terminal end of the stiffnessenhancing element comprises a portion with a cross-sectional areagreater than a cross-sectional area of a central portion of thestiffness enhancing element.
 14. The compliant constrained headbandspring of claim 13, wherein the terminal end of the stiffness enhancingelement is disposed within a groove in the retainer block.
 15. Thecompliant constrained headband spring of claim 14, wherein the terminalend of the stiffness enhancing element is configured to travel throughthe groove as the compliant constrained headband spring is opened and/orclosed.
 16. The compliant constrained headband spring of claim 15,wherein the terminal end of the stiffness enhancing element is retainedin the retainer block by a shoulder defined in the retainer block.
 17. Acompliant constrained headband spring of a headband for audioheadphones, the compliant constrained headband spring comprising: aheadband spring element; a stiffness enhancing element coupled to aretainer block coupled to the headband spring element and disposed onthe headband spring element in at least a central region of the headbandspring element, the compliant constrained headband spring exhibiting afirst stiffness in an open position and a second stiffness greater thanthe first stiffness when closed beyond a predefined point at whichterminal ends of the headband spring element are at a predefineddistance from one another; and a feature to adjust an effective lengthof the stiffness enhancing element, the feature comprising a pluralityof apertures defined in the headband spring element at differentdistances from a center portion of the headband spring element, theplurality of apertures configured to releasably retain a base of theretainer block.